A red rash on the neck may be a symptom of certain diseases, such as prickly heat, eczema, ringworm, etc. If it is accompanied by other symptoms, you should consult a doctor in time to find out the cause of the disease. 1. Prickly heat: occurs in summer or hot environment, usually in the neck, armpits, groin, etc. The main symptom is the appearance of raised pimples or small blisters on the skin, which may also be accompanied by burning and itching. 2. Eczema: When eczema grows on the neck, it will also manifest as a red rash. Eczema acute stage lesions manifested as pinhead to corn size papules, papules, serious cases can appear small blisters, vesicles oozing, self-conscious itching is intense. 3. Tinea corporis: the main pathogen of tinea corporis is Trichophyton rubrum, tinea corporis occurs in the neck, face and other parts of the body, the primary damage is a pimple or small blisters, can be gradually to the surrounding expansion and spreading, was round or irregular piece of patchy ringworm. A red rash on the neck, should promptly go to the hospital dermatology consultation, improve the relevant examination, clear cause actively cooperate with the doctor’s treatment.